Since today, April 22nd, is Earth Day we decided to take a look at one of the most important phenomena on our planet: the greenhouse effect. The greenhouse effect is when some material – like glass, plastic, or the gases in our atmosphere – allows visible light to pass through it easily but traps heat. Without the greenhouse effect, the average temperature on Earth would be a chilly -2℉, but with its help we can instead enjoy a comfortable 57℉. Too much greenhouse effect, on the other hand, and a planet could end up like Venus, the surface of which can reach a whopping 800 degrees!
In the video, we harness the greenhouse effect and the power of our sun to heat water. The black background of the solar water heater is very good at absorbing the energy contained in the sunlight. It then re-emits this energy as infrared radiation, or heat. This heat becomes trapped by the plastic cover, warming the interior of the solar heater. When cold water is passed through the pipe it collects the heat that has been gathered from the sun, emerging from the other side 70℉ warmer than it went in!
Below you can see the same thing as in the video, but in infrared! Infrared light allows us to see the temperature of everyday objects, instead of their normal color. Then, the infrared camera produces what is known as a false color image, changing it back to visible light. Since we can’t see in the infrared, it wouldn’t do any good without this step. At the bottom, it shows which temperatures correspond to which colors. This is constantly updating depending on the hottest and coldest objects in view.
We can see another example of this effect using our solar ovens.The only difference between the two is that one of them has the cover open. The oven without the cover has only heated up to about 140℉, while the covered oven is able to achieve a temperature of 280℉. When it comes to keeping you warm, or even sun baked treats, the greenhouse effect has got you covered!
Sources and Additional Information:
Earth temperature with and w/o greenhouse effect: Intergovernmental Panel on Climate Change Fourth Assessment Report. Chapter 1: Historical overview of climate change science – http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter1.pdf
Greenhouse effect image: http://www.globaled.uconn.edu/teachers_climate/images/greenhouse_effect.jpg